The present invention relates generally to integrated gasification combined-cycle (IGCC) power generation plants, and more particularly, to methods and apparatus for optimizing substitute natural gas production and heat transfer with a gasification system.
At least some known IGCC plants include a gasification system that is integrated with at least one power-producing turbine system. For example, known gasification systems convert a mixture of fuel, air or oxygen, steam, and/or carbon dioxide (CO2) into a synthetic gas, or “syngas”. The syngas is channeled to the combustor of a gas turbine engine, which powers a generator that supplies electrical power to a power grid. Exhaust from at least some known gas turbine engines is supplied to a heat recovery steam generator (HRSG) that generates steam for driving a steam turbine. Power generated by the steam turbine also drives an electrical generator that provides electrical power to the power grid.
Known gasification systems include a gasification reactor within which produces a stream of syngas. The syngas is channeled from the reactor to a plurality of apparatus that remove impurities from the syngas stream, channel at least some of the impurities back into the reactor, quench the syngas stream, and attain predetermined thermodynamic characteristics of the syngas stream. Such apparatus typically require hardware components that include multiple vessels, pumps, heat exchangers, and associated interconnecting piping. Purchasing and installing such hardware increases the capital expenditures of an IGCC plant and increases the risk of plant unavailability. Moreover, because of the increased channeling of the syngas stream through a system that includes such a large number of components, the difficulty of controlling the syngas stream temperatures and pressures is increased. Therefore, methods and/or apparatus that reduce the number of external components and the associated piping are desired.